Fuel feed and draft regulator mechanism



Jan. 18, 1955 R. GRUBB FUEL FEED AND DRAFT REGULATOR MECHANISM Filed March 8, 1952 2 Sheets-Sheet 1 iii. al

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ATTORNEYS.

Jan. 18, 1955 R. GRUBB FUEL FEED AND DRAFT REGULATOR MECHANISM Filed March 8, 1952 2 Sheets-Sheet 2 I 29, Zx ENTOR.

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WW BY ATTORNEYS.

United States Patent FUEL FEED AND DR FT REGULATOR ME H N M Roderic Grubb, Wichita, Kano, assignor to The Coleman Company, lnc., Wichita, Kans., a corporation of Kansas This invention relates to a fuel feed and draft regulator mechanism for a combustion apparatus burning a fluid fuel such as oil or gas. This invention has particular utility for jointly regulating the combustion air and fuel supply of an oil fired space heater, but it can also be advantageously employed in connection with other oil fired heating appliances operating with a naturaldraft produced by' a chimney.

In the burning of fluid fuels such as oil in a combustion apparatus, it is desired to control the amount of combustion air supplied tothe combustion'chamb'er within rather narrow limits for a particular fuel supply rate. Too little combustion air at a given fuel rate causes incomplete combustion of the fuel, which in turn produces a smoky fire, and the combustion products are carried out of the combustion chamber without the full heating capacity of the fuel being realized. On the other hand when too much combustion air is supplied, the tire is cooled by the excess air passing through the combustion chamber, which decreases the heat transfer efliciencyof the unit, and increases the heat loss in the combustion gases passed to the chimney. For thesereasons, ith as long been desired to provide an effective means for jointly controlling the fuel and combustion air rates. More specifically, it has been desired to provide a control mechanism which would maintain the quantity of combustion air supplied within the rather narrow range for optimum combustion at each fuel rate from low to high fire. This problem has long been a vexing one for the heating appliance industry, and until the present invention no fully satisfactory control mechan' m for accomplishing this result has been developed. i 4

Draft is generally understood to be the pressure difference which produces a flow of combustion air across the burner and through the combustion chamber. A natural draft is produced by a chimney orstack alone without auxiliary means such as fans or blowers for producing a forced or induced draft. The natural draft of a chimney iscaused by a difference in weights of the column 'of hot gas within the chimney and an equal column of air outside the chimney; Thus, the draft produced by a chimney of a give'nheight' is dependent primarily onthe temperature and pressure of the flue gases. However, the draft is also dependenton factors which influence the volumetric weight of the air outside of the chimney. Variations in atmospheric temperature and pressure from dayto day are sufficient to have a considerable effect on the draft produced bya'give'n chimney. Since atmospheric temperatures and pressures'cannot be directly controlled, in order to completely control the draft and thereby the combustionair' supplied to the burner, it is necessary to"equip the combustion apparatus with a control mechanism "which" automatically compensates for the variations inatmospher'i c temperatures and pressures. The fuel feed and'draft' regulator mechanism of this invention is believed ts) be an effective control mechanism to approachvthis ideal method of operation. in other words, itis believed that this invention provides a unitary controlmeans for holding a fixed relationship between the amount of combustion air and the quantity of fuel irrespective of variations in atmospheric pressure and temperature. The control mechanism of this invention also operates substantially independently of the temperature of the combustion gases as they leave the combustion chamber.

One method of varying the effective draft, or more specifically the pressure difference across the burner and combustion chamber, is to restrict the flue a selected amount by means of a variable damper mounted within the flue. Such dampers generally consist of a pivotally mounted plate which extends across the flue pipe and is equipped with an operating lever which permits the plate to be moved from substantially non-obstructing parallel alignment with the stream of the combustion gases to a position of maximum obstruction at a right angle to the stream of combustion gases. Joint control mechanisms have heretofore been provided for setting the damper in the flue outlet at a given position for each rate of fuel supply from low to high fire as determined by the setting of the fuel control valve. However, such joint control mechanisms suffer from the defect that they are not independent of variations in atmospheric temperature and pressure. A given setting of a device restricting the sizeof the flue outlet to correspond with the quantity of fuel supplied does not establish a fixed relationship between the quantity of combustion air and the amount of fuel. Variations in the temperatures of the combustion gases leaving the combustion chamber, as well as variations in atmospheric pressure and temperature, will produce a variation in the chimney draft, and thus in the resulting pressure difference across the burner and combustion chamber, which in turn will vary the amount of combustion air drawn into the burner. To make this more concrete, it is desired to point out that in previous unitary controls for joint regulation of the draft and fuel, it was more probable than not that there would be either an excess or a deficiency of combustion air.

The volume of combustion air can also be controlled by throttling the combustion air supply. Some efforts have been made to devise a joint control of the fuel and combustion air by connecting a combustion air throttling mechanism to the oil control valve. However, such control mechanisms have not proven to be satisfactory, since they either suffer from the same defects pointed out above in regard to damper-type controls, or are so mechanically complex that they are not practical structures for commercial use. Pressure regulators have also been employed to limit the maximum draft produced by the chimney. These pressure regulators operate to bleed cool air into the fine and thereby kill the draft by reducing the temperature of the combustion gases. Prior practice has been to set the pressure regulator to open and admit the relatively cool room air into the flue whenever the draft produced by the chimney substantially exceeded the maximum value which would be desired at the greatest fuel rate. These devcies were not employed for more precise regulating of the draft, and their settings ordinarily not changed after the installation of the heating appliance. in other words, even though a pressure regulator was provided, a damper control or combustion air throttling device was also provided for the actual regulation of the volume of combustion air. This invention is based in part on the discovery that a pressure regulator can be constructed which has sufficiently linear operating characteristics over the operating draft range of a combustion appliance such as a space heater to permit it to be coupled with the oil control valve, and thereby jointly regulate the draft and fuel supply. At each setting of the oil control valve, the pressure regulator is set at a corresponding position to maintain the required pressure difference across the burner and combustion chamber to draw the correct amount of combustion air into the burner. This method of joint regulation of the fuel and combustion air has the surprising advantage that it is substantially independent of variations in atmospheric temperature and pressure and of the temperature of the combustion gases. This method of operation will become clearer by the subsequent detailed explanation.

It is therefore a primary object of this invention to develop a fuel feed and draft regulator mechanism which employs a pressure regulator to control the pressure difference across the burner and combustion chamber and thereby the quantity of air supplied for each fuel rate from low to high fire. A further object of this invention is to develop a pressure regulator structure which has 'sufliciently linear operating characteristics to permit it to be coupled with the oil valve by a joint control means. A still further object of this invention is to develop a simple and inexpensive mechanical arrangement for accomplishing the above results. Further objects and advantages will appear as the specification proceeds.

The invention is shown, in several illustrative embodiments, by the accompanying drawings, in which- Figure 1 is a transverse sectional view of a space heater equipped with the fuel feed and draft regulator mechanism of this invention showing the pressure-regulator mounted in the side of a box extending laterally from the flue outlet; Fig. 2, a detail view of a portion of the structure of Fig. 1 showing particularly the pressure regulator; Fig. 3, a broken rear View in elevation of the space heater of Fig. 1 showing the joint regulation mechanism for correspondingly setting the pressure regulator and fuel valve; Fig. 4, a top plan view of a portion of the structure shown in Fig. 3, showing particularly the operating lever and cooperating stepped support; Fig. 5, a fragmentary side elevational view of a modified structure in which the pressure regulator is mounted in the side of the flue; Fig. 6, a top sectional view of the structure shown in Fig. 5; Fig. 7, a fragmentary cross-sectional view of the structure of Fig. 5; and Fig. 8, a fragmentary transverse sectional view of a modification in which the pressure regulator is mounted in the side wall of the combustion chamber adjacent the flue outlet.

The fuel feed and draft regulator mechanism of this invention can advantageously be employed in a combustion apparatus providing a combustion chamber equipped with a fuel burner and having a combustion air inlet near the burner for drawing air from the exterior atmosphere and an outlet for the hot combustion gases at a spaced distance from the inlet, the outlet communicating with a flue leading to a chimney. In this type of combustion apparatus the volume of combustion air drawn into the combustion apparatus is proportional to the pressure difference across the burner and combustion chamber resulting from the natural draft of the ch mney. The fuel feed and draft regulator structure of th1s 1nvent1 on includes in general a fuel supply pipe equipped with an adjustable control valve, an inlet into the flue communicating with the exterior atmosphere for delivering relatively cool air into the flue to dilute the hot combustion gases, whereby the temperature of the gases 1n the chimney is reduced and thereby the draftlnducing pressure difference across the burner and combust on chamber, and a pressure-responsive air valve controlling the inflow of cool air through the inlet into the flue. The pressure-responsive air valve should be yieldably urged to 1ts closed position by means exerting a selectlvely variable force thereon while permitting the valve to open in proportion to the pressure difference thereacross. The combination of this invention also in cludes as an element thereof an adjustment means for simultaneously setting the fuel valve and the pressure- IGSPOIlSlVC air valve at corresponding positions. This adustment means should progressively increase the closing force exerted by the air valve closing means so that the draft Wlll increase in proportion to the increased rate at which fuel is supplied to the burner. All of these elements of the combination comprehended within the scope of this invention cooperate to maintain a substantially fixed relationship between the volume of combustion air antd the amount of fuel over a wide range of fuel input ra es.

In the following detailed description of the fuel feed and draft regulator structure constructed in accordance with the principles of this invention, it is described in connection with a space heater equipped with a pot-type burner. However, it will be understood that this invention is not limited to this specific application, and that the particular application described is merely illustrative.

In the illustration given with particular reference to Fig. 1, designates the outer casing of a space heater unit, 11 designates the inner casing providing a combustion chamber 12, and 13 designates a burner casing providing a burner chamber 14. An opening 15 is provided between combustion chamber 12 and burner chamber 14, and a pot-type burner 16 is supported within chamber 14 so that it extends upwardly through opening 15. The combustion air enters through an opening 17 in the bottom of burner chamber 14 and passes upwardly around the sides of the burner pot 16 and into the burner pot through a plurality of apertures 18 arranged in rows. The fuel oil is supplied through fuel supply pipe 19 and is discharged onto the bottom of the pot burner 16 from which it is vaporized and combined with the combustion air in the upper. regions of the burner pot so that when in operation flames extend upwardly from within burner pot 16 into combustion chamber 12. The

path of movement of the combustion air and combustion.

gases is indicated by the arrows in Fig. 1. The air to be heated passes upwardly through the heating space 20 provided by the casings 10 and 11, entering through the bottom of the casing and passing outwardly at the top of the casing as indicated by thearrows in Fig. 1.

The hot combustion gases are exhausted from combustion chamber 12 through flue outlet 21 which communicates with a flue 22, which in turn leads to a chimney 23. It will be understood from the above discussion that the natural draft of chimney 23 produces the flow of combustion air through the burner and combustion chamber, and that the volume of air flowing into burner chamber 14 through opening 17 will be proportional to the pressure difference across burner chamber 14 and combustion chamber 12.

Preferably, the pressure-responsive air valve for introducing relatively cool room air into flue 22 is located in the outside wall of a box 24 extending laterally from flue 22. In the illustration given, box 24 is mounted between the outer casing 10 and the inner casing 11 of the space heater, and provides a chamber 25 communicating with the interior 26 of flue 22. The pressure-responsive air valve which is designated generally as V controls the inflow of cool air through inlet opening 27 in the outside wall of box 24. It is preferred to locate the air valve in the wall of a box extending laterally from the flue outlet so that the air valve will be out of the line of flow of hot combustion gases. This improves the operation of the air valve since the pressure within the laterally extending box, such as box 24, is not as subject to momentary fluctuations as the pressure within flue 22 due to the high velocity of the gases through the flue. Also, the air valve is protected from having its operation impaired by the accumulation of soot thereon, and it does not interfere with or obstruct the movement of the c mbuStion gases through the flue. However, the air valve can be located in other positions with good results, as will subsequently be described in connection with modified forms of the present invention.

Various types of air valves can be used to control the inflow of room air into the flue, but it is preferred that a pivotally mounted air vane be employed for this purpose. In the illustration given, there is shown an air vane 28 pivotally mounted within opening 27. As shown more clearly in Fig. 3, air vane 28 is pivotally mounted on pins 29 and 30. Air vane 28 provides outer and inner pressure receiving faces 31 and 32 on which the pressure difference across the vane acts to pivot the vane about the pivotal axis defined by the alignment of pivot pins 29 and 30. The pivotal axis of air vane 28 preferably divides the outer and inner pressure receiving faces 31 and 32 into areas of unequal size on each side of the axis so that a pressure differential across the vane will tend to rotate the vane on the axis to an open position. This would not occur if the areas of the pressure-receiving faces above and below the pivotal axis were of the same size, since there would be just as much force tending to turn the vane clockwise about the axis as counterclockwise.

'In'the illustration given, and, preferably air vane 28 is formed in the shape of a hollow disk having outwardly convex surfaces 31 and 32. This construction is indicated more clearly in Fig. 2. This hollow, outwardly convex construction facilitates the operation of the air vane.

Air vane 28 should be yieldably urged to its closed posi- 7 tion by means exerting a selectively variable force thereon but permitting the vane to open in proportion to the pressure difference thereacross. This is preferably accomplished by distributing the mass of air on vane 28 so that the center of mass of the vane is positioned with respect to its pivotal axis so as to exert a force urging the vane to its closed position. In the illustration given as indicated more clearly in Fig. 2, air vane 28 is provided with a weight 33 attached to the inner wall of the outer pressure receiving face 32 below the pivot axis provided by pins 29 and 30. Preferably, the mass of weight 33 is substantially greater than the mass of the rest of vane 28.

It will thus be apparent that the center of mass of the lower'portion of vane 28 is displaced outwardly from the plane passing through the pivot axis and the center of mass of the lower portion of the vane. This tends to resist the rotation of air vane 28 about its axis in a counterclockwise direction as viewed in Figs. 1 and 2. Preferably also the portions of pressure receiving faces 31 and 32 below the pivotal axis are of considerably smaller areas than the portions of the faces above the axis, so that a drop in pressure inwardly across the vane will tend to rotate it in a counterclockwise direction about its axis as viewed in Figs. 1 and 2. Thus, the distribution of the mass of the vane with relationship to its pivot axis tends to rotate it clockwise to a closed position, while the force of atmospheric pressure acting on the outer face 31 tends to rotate the vane to an open position in a counterclockwise direction. Open positions of the air vane 28 at which the force exerted by the pressure difference across the vane exceeds the closing force exerted by weight 33 are shown in Figs. 1 and 2.

When air vane 28 is circularly shaped as preferred, the pivot axis provided by pivot pins 29 and 39 should extend chordally with respect to the disk, as indicated more clearly in Fig. 3. The pivot axis should also be nonvertical, since in a vertical position weight 33 will not exert an effective closing action on the vane.

Means should be provided for varying the closing force exerted by the closing means on air vane 28. When vane 28 has its mass distributed with respect to the pivot axis so that it tends to rotate to a closed position against the force of the pressure difference across the vane, this can be most easily accomplished by varying the inclination of the pivot axis. Therefore, it is preferred to provide a shiftable support designated generally as 34 disposed about air vane 28 so that when the air vane is pivotally connected to the support it will extend across a portion of the inlet to flue 22. In the illustration given, the inlet to flue 22 through box 24 terminates in a circular opening 27, and there is rotatably supported within opening 27 a support ring 35. Support ring 35 is equipped with peripherally spaced rollers 36 which ride within the annular channel member 37, as shown more clearly in Fig. 2. Thus, the rotation of support ring 35 to which air vane 28 is pivotally connected by pins 29 and 30 varies the inclination of the pivot axis, and this in turn varies the closing force exerted by weight 33. On the inner edge of ring 35 above the pivot axis there is preferably provided a stop 38 to limit the clockwise rotation of air vane 28 under the influence of weight 33. In the illustration given, air vane 28 will normally come to rest in a generally vertical closed position in contact with stop 38. As the inclination of the pivot axis of air vane 28 is progressively decreased relative to the horizontal by rotating ring 35 and air vane 28 in a clockwise direction as viewed in Fig. 3, the pressure difference across the air vane required to open it a given amount likewise increases. As indicated above, it has been found that this variation in the force required to open the airvane a given amount is sufficiently linear that the airvane can be coupled to the fuel control valve and adjustment means provided for simultaneously setting the fuel valve and the air vane, and that the result of this joint control will be that a substantially fixed relationship can be maintained between the volume of combustion air and the amount of fuel over a wide range of fuel input rates.

In the illustration given, fuel line 19 is equipped with an adjustable control valve 39, as indicated more clearly in Fig. 3. Control valve 39 can be of any suitable type, but preferably it is capable of actuation by the rotation of an actuating member. In the illustration given, valve 7 39 is provided with a rotary handle member 40 which operates a cam for the movement of the valve stem vertically within the valve casing by a mechanism (not shown). Since the valve shown is one of well-known construction and no claim is made thereto herein, a further detailed description is believed unnecessary. It is sufficient to say that handle member 40 is attached to a tubular member 41 slidably receiving the flattened reduced end 42a of actuating rod 42. The reduced end 42a is slidably mounted within tubular member 41 to permit vertical movements of actuating member 42 with respect to member 41 while at the same time producing a rotation of the member 41 when rod 42 is rotated due to its being rotatably locked to member 41 .by inward depression 41a. There is provided connecting means between the adjustable support means for air vane 28 and actuating rod 42. This is preferably accomplished in the following manner. At a point adjacent air vane 28, actuating rod 42 is equipped with spaced collars 43 and 44 which are adjustably locked to rod 42 by set screws 45 and 46. A sleeve member 47 slidably receives rod 42 and is held in position upon the rod between the collars 43 and 44, as shown in Fig. 3. Fixed to sleeve 47 is a laterally extending link 48 having a slot 49 therein receiving the pin 50 which is fixed to the outer face of rotatable ring 35. The slot 49 is elongated so as to permit relative movement of the pin 50 therein when the rotatable ring 35 is moved upwardly and downwardly by link 48. It is preferred to equip rod 42 and casing 10 with cooperating means whereby the rotation of rod 42 is limited without raising the rod. Any suitable means of accomplishing this purpose may be employed. In the illustration given as shown more clearly in Fig. 3, the rear wall of casing 10 near the top thereof is provided with a platform member 51 having a vertical flange 52 secured to the casing. Upon the horizontal platform is mounted vertically extending curved plate 53 having a stepped upper edge. Plate 53 and platform 51 cooperate to provide vertically spaced steps a, b, c, d, e, and 7. Rod 42 extends through an opening in platform 51 and is provided with a laterally turned end 42b adapted to serve as an operating handle with which rod 42 can be simultaneously elevated and rotated so as to seat the inner portion of turned end 42b on the steps provided by platform 51 and the upper edge of plate 53. The vertical portions of the upper edge of plate 53 serve as stops to limit the rotation of rod 42 and to compel the rod to be raised successively to seat it on the horizontal portions of the upper edge of plate 53 providing the steps b to f. The steps may be formed in any desired arrangement, but are preferably so placed as to require a raising of the rod 42 for each predetermined degree of rotation of rotary handle 40 for actuating the valve whereby the inclination of the pivot axis of air vane 28 is correspondingly changed in position to that of valve 39. If desired, platform 51 may be provided with insignia as shown in Fig. 4, designating the different positions of the feed valve and indicating the rate of feed.

In order to insure that rod end 42b is maintained in a fixed position to which it is set, it is preferred to equip rod 42 with a fixed collar 54 providing a seat for the compression spring 55 extending between the collar 54 and platform 51.

In Figs. 5, 6, and 7 there is shown a modification of the fuel feed and draft regulator mechanism of Figs. 1 to 4. The structure shown is substantially the same as that previously described, and the corresponding parts have the same numbers applied thereto, except that the numbers are primed to indicate that a modification is being illustrated. One difference between the structure of Figs. 5-7 and that previously described is that air vane 28 is mounted directly in the side of flue outlet 22'. Also, weight 33' is mounted on the inner wall of the inner pressure-receiving face 32' above the pivot axis, and the pivot axis provided by pins 29' and 30' extends above center. Stop 38 is placed below the pivot axis. Air vane 28' operates in substantially the same way as air vane 28, except that it opens by rotating clockwise as viewed in Fig. 7.

A still further modification is shown in Fig. 8. In this figure the air vane 28" (otherwise the same as air vane 28) is shown mounted directly in the side of the inner furnace casing 11" just below flue outlet 21". There is preferably provided a baffle plate 101 extending inwardly and upwardly just below inlet opening 27 to prevent undue turbulence in the region just inside of air vane 28 and the accumulation of soot on the air vane.

Operation position as indicated by the number 1 on the lowermost step a. This movement rotates rod 42 connected to rotary handle 40 of the valve actuating means and causes vane 28 is set to exert a closing force sufficient to maintain the desired draft for this low rate of fuel. For example, the low draft position of air vane 28 is indicated in Fig. 3. In this position, weight 34 exerts a relatively small closing force on the air vane and therefore permits a relatively free opening of the vane. This admlts more room air across the vane, andthe flue gases are therefore diluted and cooled to reduce the natural draft of the chimney to the required pressure difference across the burner and combustion chamber to draw in the optimum amount of air for burning the fuel at the low fire rate. If the fuel rate is to be'increased, the turned end 42b of rod 42, which provides a handle, is grasped and raised to bring the end of the rod upon the next step, for example on step b indicated by the number 2 in Fig. 4, and

the rod is similarly-raised and rotated for the increased fuel rates'up to the high fire fuel rate on step as indicated by the number 6 in Fig. 4. In each of the raising movements, the link 48, is lifted and through its engagement with pin 50 of rotatable support ring 35, changes the position of ring 35 to cause air vane 28 to pivot less readily and to allow air to fiow in lesser quantities into chamber '25 provided by box 24. If the modification of Figs. to 7 is employed, the air will be directly admitted to the flue, while if the modification of Fig. 8 is employed, the air will be admitted into the upper portion of the combustion chamber itself wherein it will combine with the combustion gases and move outwardly into the flue. As already indicated, decreasing the amount of outside air admitted to flue 26 by air vane 28, increases the mean temperature in the flue, and thus increases the draft. It will be understood from the explanation of the cause of natural draft as previously explained, that the increase in the pressure difference across the burner and combustion chamber resulting from the decrease in the amount of room air admitted to the flue outlet is a secondary phenomena caused by the increased temperature of the combustion gases in the chimney.

As valve 39 is opened by the rotation of rod 42, support ring 35 is rotated in a clockwise direction as viewed in Fig. 3 so that the pivot axis of air vane 28 provided by pivot pins 29 and 30 progressively decreases in inclination with respect to the horizontal. This causes weight 33 to exert a relatively greater closing force on the air vane, and therefore the air vane opens a correspondingly smaller amount in response to a given pressure difference thereacross. It will be understood that in order to minimize the effect of friction on the movements of air vane 28, that it will be preferred to support pivot pins 29 and 30 in bearings adapted to minimize the frictional resistance to the rotation of the pivot pins. A reverse movement of the handle or rod end 42 results in a lowering of rod 42 and a corresponding rotary movement of ring support 35 in the opposite direction (counterclockwise as viewed in Fig. 3), the rotary valve handle also being turned so as to reduce the flow of oil through the valve.

It will be understood that the draft regulator control or more specifically the air valve V, may be arranged in any desired position, and may be above or on the same level with flue 22.

In the foregoing operations, the rotary handle 40 for controlling the actuation of the valve stem'and the actuating rod 42 therefore are restrained against rotation without a corresponding vertical movement of the rod and such vertical movement of the rod is utilized for the arcuate movement of the support ring 35 of air valve V. The entire control mechanism is arranged in a single line and in a compact arrangement at the rear of the casing, the only part requiring manual operation being the bandle end 42a of the rod 42. By movement of this one part the operator is able to adjust accurately the desired fuel feed rate while automatically changing the setting of air vane 28 to bring about a desired pressure differential between the inside of the burner and the atmosphere. As previously indicated, the operating characteristics of air vane 28 are sufliciently linear that it can be brought to a setting required to maintain the pressure difference across the burner and combustion chamber which will supply the optimum amount of air for burning the fuel at the selected rate from low to high fire. Also, it is desired to emphasize again that the operation of air vane 28 is such that the corresponding pressure difference for each fuel input rate is maintained substan- 8 tially independent of variations in atmospheric pressure and temperature, and of variations in the temperature of the combustion gases as they enter the flue outlet.

This application is a continuation-in-part of my copending. application United States Serial No. 62,756, filed November 30, 1948, now abandoned.

While in the foregoing specification, specific structures have been set out in considerable detail for purpose of illustrating embodiments of the invention, it will be understood that many of the structural details set forth may be varied widely by those skilled in the art without departing from the spirit of this invention.

1 claim:

1. A combustion apparatus providing a combustion chamber equipped with a fuel burner and having a combustion air inlet near said burner drawing air from the exterior atmosphere and an outlet for the hot combustion gases at a spaced distance from said inlet, said outlet communicating with a flue leading to a chimney, whereby the volume of combustion air drawn into said combustion apparatus is proportional to the pressure difference across said burner and said combustion chamber, a fuel feed and draft regulator mechanism, comprising a fuel supply pipe operatively associated with said burner equipped with an adjustable control valve, means forming an inlet into said flue communicating with the exterior atmosphere for delivering relatively cool air into said flue to dilute the hot combustion gases, whereby the temperature of the gases in said chimney is reduced and thereby the draft-inducing pressure difference cross said burner and combustion chamber, an air vane controlling the inflow of cool air into said flue through said inlet, a shiftable support disposed about said air vane, said air vane extending across a portion of said inlet and being pivotally mounted on said support on a non-vertical axis, means mounting said support for movement in a plane to vary the inclination of said axis, said axis dividing the inner and outer pressure receiving faces of said vane into areas of unequal size above and below said axis so that a draft-created pressure difference across said vane will tend to rotate said vane on said axis to an open position, the center of mass of said vane being positioned with respect to said pivot axis so as to exert a force urging said vane to its closed position, an adjustment means for simultaneously setting said fuel valve and said shiftable support, said adjustment means progressively decreasing the inclination of the axis of said air vane relative to the horizontal by shifting said support as said fuel valve is opened so that less air will be admitted to said flue and the draft will therefore increase in proportion to the increased rate at which fuel is supplied to the burner, whereby a substantially fixed relationship can be maintained between the volume of combustion air and the amount of fuel over a wide range of fuel input rates.

2. In a combustion apparatus providing a combustion chamber equipped with a fuel burner and having a combustlon air inlet near said burner drawing air from the exterior atmosphere and an outlet for the hot combustion gases at a spaced distance from said inlet, said outlet communicating with a flue leading to a chimney, whereby the volume of combustion air drawn into said combustion apparatus is proportional to the pressure difference across said burner and said combustion chamber, a fuel feed and draft regulator mechanism, comprising a fuel supply pipe operatively associated with said burner equipped with an adjustable control valve, means forming an inlet into said flue communicating with the exterior atmosphere for delivering relatively cool air into said flue to dilute the hot combustion gases, whereby the temperature of the gases in said chimney is reduced and thereby the draft-inducing pressure difference across said burner and combustion chamber, a pressure-responsive disk extending across a portion of said inlet for control ling-the inflow of cool air into said flue through said inlet, a rotatably mounted support disposed about the periphery of said disk, said disk being pivotally mounted on said support on a non-vertical axis extending chordally with respect to said disk so that a draft created pressure difference across said disk will tend to rotate it to an open position, the center of mass of said disk being positioned with respect to said axis to exert a force urging said disk to its closed position, means mounting said support for rotation in a plane to vary the inclination of said axis so that as said axis approaches the horizontal more force will be required to open said disk, an adjustment means for simultaneously setting said fuel valve and said support, said adjustment means progressively decreasing the inclination of the pivotal axis of said disk with respect to the horizontal by rotating said support as said fuel valve is opened so that less air will be admitted to said flue and the draft will therefore increase in proportion to the increased rate at which fuel is supplied to the burner, whereby a substantially fixed relationship can be maintained between the volume of combustion air and the amount of fuel over a wide range of fuel input rates.

3. The fuel feed and draft regulator mechanism of claim 2 in which said rotatably mounted support is in the form of a ring, and said disk is chordally pivoted with respect to both said disk and said ring.

4-. In a combustion apparatus providing a combustion chamber equipped with a fuel burner and having a combustion air inlet near said burner drawing air from the exterior atmosphere and an outlet for the hot combustion gases at a spaced distance from said inlet, said outlet communicating with a flue leading to a chimney, whereby the volume of combustion air drawn into said combustion apparatus is proportional to the pressure difference across said burner and said combustion chamber, a fuel feed and draft regulator mechanism, comprising a fuel supply pipe operatively associated with said burner equipped with an adjustable control valve, means forming an inlet into said flue communicating with the exterior atmosphere for delivering relatively cool air into said flue to dilute the hot combustion gases, whereby the temperature of the gases in said chimney is reduced and thereby the draft-inducing pressure difference cross said burner and combustion chamber, the inlet into said flue for the admission of cool air providing a cylindrical portion having a generally horizontal axis, a ring rotatably mounted within said cylindrical portion with the axis of said ring substantially in alignment with the axis of said cylindrical portion of the inlet, a pressure responsive disk pivotally mounted on said ring and extending thereacross for controlling the inflow of cool air into said flue through said inlet, the pivot axis of said disk being non-vertical and extending chordally with respect to both said disk and said ring so that a draft-created pressure diiference across said disk will tend to rotate said disk on said axis to an open position, the portions of the in ner and outer pressure receiving faces of said disk below said axis being smaller than the portions above said axis, the center of mass of the portion of said disk below said axis being displaced outwardly from the plane including said pivot axis and the center of mass of the lower portion of said air vane so that the center of mass of the lower portion of said vane exerts a closing force on said disk, stop means for limiting the outward rotation of the upper part of said disk beyond its closed position, means mounting said ring for rotation in a plane to vary the inclination of said axis so that as said axis approaches the center of mass of the upper portion of said disk it will exert more closing force on said disk, and adjustment means for simultaneously setting said fuel valve and said ring, said adjustment means progressively decreasing the inclination of the pivot axis of said disk with respect to the horizontal by rotating said ring as said fuel valve is opened that less air will be admitted to said flue and the draft will therefore increase in proportion to the increased rate at which fuel is supplied to the burner, whereby a substantially fixed relationship can be maintained between the volume of combustion air and the amount of fuel over a wide range of fuel input rates.

5. in a combustion apparatus providing a combustion chamber equipped with a fuel burner and having a combustion air inlet near said burner drawing air from the exterior atmosphere and an outlet for the hot combustion gases at a spaced distance from said inlet, said outlet communicating with a flue leading to a chimney, whereby the volume of combustion air drawn into said combustion apparatus proportional to the pressure difference across said burner and said combustion chamber, a fuel feed and draft regulator mechanism, comprising a fuel supply pipe operatively associated with said burner equipped with an adjustable control valve, means forming an inlet into said flue communicating with the exterior atmosphere for delivering relatively cool air into said flue to dilute the hot combustion gases, whereby the temperature of the gases in said chimney is reduced and thereby the draft-inducing pressure difference cross said burner and combustion chamber, a pressure-responsive disk extending across a portion of said inlet for controlling the inflow of cool air into said'flue through said in let, a rotatably mounted support disposed about the periphery of said disk, said disk being pivotally mounted on said support on a non-vertical axis extending chordally with respect to said disk so that a draft-created pressure difference across said disk will tend to rotate it to an open position, the center of mass of said disk being positioned with respect to said axis to exert a force urging said disk to its closed position, means mounting said support for rotation in a plane to vary the inclination of said axis so that as said axis approaches the horizontal more force will be required to open said disk, an actuating rod connected to said fuel control valve and actuating said valve by rotating about the longitudinal axis of said rod, connecting said actuating rod to said valve arranged to permit said rod to move longitudinally while maintaining its rotational connection with said valve to actuate said valve, link means connected to said rod and said rotatably mounted support so that said support is rotated by the longitudinal movement of said rod, and means for limiting the rotation of said rod until the same is moved longitudinally an established distance, whereby the longitudinal movement of said rod selects the pressure difference to be maintained across said burner and combustion chamber and the rotation of said rod selects the corresponding amount of fuel.

6. In a combustion apparatus providing a combustion chamber equipped with a fuel burner and having a combustion air inlet near said burner drawing air from the exterior atmosphere and an outlet for the hot combustion gases at a spaced distance from said inlet, said outlet communicating with a flue leading to a chimney, whereby the volume of combustion air drawn into said combustion apparatus is proportional to the pressure difference across said burner and said combustion chamber, a fuel feed and draft regulator mechanism, comprising a fuel supply pipe operatively associated with said burner equippec with an adjustable control valve, means forming an inlet into said fluecornmunicating with the exterior atmosphere for delivering relatively cool air into said flue to dilute the hot combustion gases, whereby the temperature of the gases in said chimney is reduced and thereby the draft-inducing pressure difference cross said burner and combustion chamber, said inlet terminating in an annular channel, a ring rotatably mounted within said annular channel, a hollow disk having outwardly convex surfaces pivotally supported within said ring and extending thereacross for controlling the inflow of cold air into said flue through said inlet, the pivot axis of said disk extending in a non-vertical line chordally of said disk and said ring so that a draft-created pressure difference across said disk will tend to rotate said disk to an open position, the lower part of said disk being weighted to urge said disk to a closed position, stop means for preventing the upper part of said disk from swinging outwardly beyond said closed position, an actuating rod for simultaneously rotating said ring and varying said fuel valve, means connecting said actuating rod to said fuel valve permitting said rod to be moved longitudinally while maintaining a rotational connection with said valve for changing the position of said valve, link means pro viding a connection between said rod and said ring s that said ring is rotated by the longitudinal movement of said rod, and means for limiting the rotation of said rod until the same is moved longitudinally an established distance, said link means progressively decreasing the inclination f the pivot axis of said disk with respect to the horizontal by rotating said ring in a plane as said fuel valve is opened by the rotation of said rod, whereby the longitudinal movement of said rod selects the pres sure difference to be maintained across said burner and combustion chamber and the rotation of said rod selects the corresponding amount of fuel.

7. The fuel feed and draft regulator structure of claim 6 characterized by the further fact that said inlet means comprises a box mounted on the side of said combustion apparatus and extending laterally from said flue, said box having a circular opening in an outer wall thereof and providing a chamber interiorly communicating with said flue so that cold air entering through said opening will pass into said fine to dilute the flue gases therein, and said rotatably mounted ring and said disk. being mounted in the circular opening of said box.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS 12 Miller Mar. 9, 1943 Martin Mar. 28, 1944 Martin May 30, 1944 Miller et a1. Nov. 21, 1944 Jensen Dec. 28, 1948 

